Engine knocking to the untrained ear is deceptive and often misleading. It is rare that the boxer engine blow up after the owner reports an engine noise. You'll need to provide more details regarding the so-called knock so we can accurately diagnosis your issue. So, here are the hints; 1- Frequency of the knock. 2- From what area of the engine does the knock come from? 3- Does it go away with RPM changes? 4- Clutch in or out? 5- Hot or cold? 6- What engine oil is in the engine ans how many miles on this oil? What brand filter? Finally, try this. When you next cold start the engine, let it run for 10 seconds cold and shut it off with the kill switch leaving the key on. Count the seconds from the time you shut it off and when the oil light comes on and report back here.

It could be the throttle bodies. The shaft wears and allows the butterfly to move in pulse with the intake. I would call that a tapping sound but some might call it knocking. Easy enough to put a finger on the shaft while the bike is running and see if it makes a difference.

It could be the throttle bodies. The shaft wears and allows the butterfly to move in pulse with the intake. I would call that a tapping sound but some might call it knocking. Easy enough to put a finger on the shaft while the bike is running and see if it makes a difference.

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There is a flat silver plate which is on the engine side of the throttle body that the throttle cable connects to. When I put a finger on that plate and apply some pressure the clicking noise even stops. I have the rebuild kit for both TB's which will be installed this winter.

For now, it sounds like a set of false teeth from a trick and joke shop

Hey all. I hear a slight knocking on my bike. If I'm facing the bike it's most clearly heard from the left side.

The valves sound really nice. I've done the chain tensioner mod which is on the other side.

Maybe I just need to rebalance and idle the carbs?

It's not that there's any problem right now I would just like to prevent a complete rebuild or some kind of worse failure on a trip. Any advice would be appreciated. Thx.

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No carbs on your boxer...those are fuel injection throttle bodies. Before you tackle any adjustments, read some more about how and why the adjustments are made. Also DO NOT DISTURB THE LITTLE BLACK BOX ON THE LH SIDE THROTTLE BODY. That is the throttle position sensor and is factory set and marked with blue paint. Also, do not adjust the throttle stop screws. Doing so will leave you with a bike that does not run correctly. You need to better understand how the fuel system works on the boxer before you break out the tools. I would recommend your buddy up with someone experienced in your neighborhood who will keep you out of trouble while you learn just how and why adjustments are carried out.

No carbs on your boxer...those are fuel injection throttle bodies. Before you tackle any adjustments, read some more about how and why the adjustments are made. Also DO NOT DISTURB THE LITTLE BLACK BOX ON THE LH SIDE THROTTLE BODY. That is the throttle position sensor and is factory set and marked with blue paint. Also, do not adjust the throttle stop screws. Doing so will leave you with a bike that does not run correctly. You need to better understand how the fuel system works on the boxer before you break out the tools. I would recommend your buddy up with someone experienced in your neighborhood who will keep you out of trouble while you learn just how and why adjustments are carried out.

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Calm down. He hasn't responded to your first suggestion yet.

I second def's suggestions in his previous post. It may help to use a stethoscope/long screwdriver/woden dowel/piece of hose to try to isolate where the 'knocking' is comming from.

Engine knocking to the untrained ear is deceptive and often misleading. It is rare that the boxer engine blow up after the owner reports an engine noise. You'll need to provide more details regarding the so-called knock so we can accurately diagnosis your issue. So, here are the hints; 1- Frequency of the knock. 2- From what area of the engine does the knock come from? 3- Does it go away with RPM changes? 4- Clutch in or out? 5- Hot or cold? 6- What engine oil is in the engine ans how many miles on this oil? What brand filter? Finally, try this. When you next cold start the engine, let it run for 10 seconds cold and shut it off with the kill switch leaving the key on. Count the seconds from the time you shut it off and when the oil light comes on and report back here.

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As a matter of curiosity I did the cold shut down test you outlined above and got ~12sec. on my bike. I would assume the longer the time, the better the health of the engine. Is there a number which indicates "bad"?

As a matter of curiosity I did the cold shut down test you outlined above and got ~12sec. on my bike. I would assume the longer the time, the better the health of the engine. Is there a number which indicates "bad"?

Cheers, James

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This test is rather crude and would show signs of loose lower end bearings if the cold oil pressure was not sustained for several seconds as you observed.

The trick is to do this occasionally before you change oil and after you change oil. You'll get a reasonable baseline with which you can judge oil viscosity, engine bearing clearance and how temperatures effect oil viscosity and engine clearances.

I would speculate that good 15w-50 oil in a boxer with normal bearing clearances at 75 F. ambient, the ~12 seconds cold oil pressure bleed down you observed is normal.

I just did my oil pressure bleed down on my '01 with ~50,000 miles and old 15w-50 Mobil 1 oil. About 10 seconds cold (ambient is 70 F.). I had some errands to run so when I returned to the garage with the bike hot, I did it again. This time about 2 seconds with hot oil and engine. I consider those nominal times. Remember, there are many variables in this test so use caution when evaluating the information.

Engine knocking to the untrained ear is deceptive and often misleading. It is rare that the boxer engine blow up after the owner reports an engine noise. You'll need to provide more details regarding the so-called knock so we can accurately diagnosis your issue. So, here are the hints; 1- Frequency of the knock. 2- From what area of the engine does the knock come from? 3- Does it go away with RPM changes? 4- Clutch in or out? 5- Hot or cold? 6- What engine oil is in the engine ans how many miles on this oil? What brand filter? Finally, try this. When you next cold start the engine, let it run for 10 seconds cold and shut it off with the kill switch leaving the key on. Count the seconds from the time you shut it off and when the oil light comes on and report back here.

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Wow guys, thanks for all the advice! Sorry it's taken me a while to get back with the answers but here they are along with a link to a youtube video I made trying to capture idle and a slight rev.

1. frequency seems pretty consistant
2. sounds like just under the cylinder head (if your facing the bike front left)
3. No, it's more noticable when it's idling but I can still feel it (or so I think) when its up around 4000
4. clutch in or out has no effect
5. pretty consistant hot and cold (maybe a little more pronounced when hot)
6. 20w-50 castrol synthetic. almost 3000 on this change (engine has 48,000) filter is bmw,
Cold start test was 6 seconds until light came on

that bike sounds smooth and quiet to me, especially when compared to the one I ride daily.

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Since doing the valves and TBs I've really become attuned to the motor so I really can't tell anymore. That's why I ask. I was worried for quite awhile because PO had the valves cranked down so hard that they may have been messed. The bike works fine tho. Theres a lot of power and other than the what I assume is normal weird jumpy throttle stuff under 3500 its ok.

Doesn't sound too much different from mine. Grab a big screwdriver and put the end of the handle up to your ear and put the blade on different parts of the motor and see if you can better pinpoint the origins of the sound.

Throttle bodies don't knock. They might click a little. Twist the throttle ever so slightly and you can hear the change in the clicking sound. My guess is that what you are hearing is from crankshaft end play. Loudest at idle under no load. Goes away or can't be heard while riding. Probably your knock is worse after engine is at operating temp. Mine sounds bad just before I shut it down after a ride. Have 162,000 miles on it. I quit fearing sounds from it a long time ago.